Developing method for plain paper copying

ABSTRACT

The specification teaches a dielectric belt having a metal backing. The belt is uniformly charged by some type of charging device such as a corona beam whereafter it is uniformly toned by a magnetic brush. Then, a stencil or screen which is capable of acting as an ion modulator is used to screen a flow of ions into a pattern to strike the coated belt surface. The ions will neutralize the charge in an image pattern and thus allow the image pattern toner to be loosely held in a background of tightly attracted toner. Thereafter, a plain paper sheet is rolled in contact with the surface to pick up the loosely bonded toner and extract an image from the belt onto the plain paper sheet. The belt is not cleaned, but is recharged to bring up the charge up to full strength in the formerly discharged areas as well as in the areas not discharged and the entire belt is retoned to a uniform density once again for a repeat with the same or a new modulating screen or stencil.

[451 Aug. 19, 1975 [54] DEVELOPING METHOD FOR PLAIN PAPER COPYING [75] Inventor: Curt Robert Raschke, Warrensville Heights, Ohio [73] Assignee: Addressograph-Multigraph Corporation, Cleveland Ohio 22 Filed: Jan. 30, I974 211 Appl. No.: 438,161

[52] US. Cl. 346/74 ES; 96/l C [51] Int. Cl. G036 15/16 [58] Field of Search 346/74 ES, 74 lB, 74 EB 346/74 EX, 74 W, 74 P; 355/17; 96/] C, l E

[56] References Cited UNITED STATES PATENTS 2.901.374 8/1959 Gundlach 346/74 ES 3.l6l).09l l2/l964 Schwerlz 346/74 ES 3.299.806 l/l967 Sawada 346/74 ES 3,438.053 4/l969 Howell 4 346/74 ES 3,6l LUIH lU/l97l Ring 346/74 ES Primary lzlruminer-Daryl W. Cook AA'ATSIHIH livaminer.lay P. Lucas Armrney, Agent, or Firrn-Ray S. Pyle 5 7 ABSTRACT The specification teaches a dielectric belt having a metal backing. The belt is uniformly charged by some type of charging device such as a corona beam whereafter it is uniformly toned by a magnetic brush. Then, a stencil or screen which is capable of acting as an ion modulator is used to screen a flow of ions into a pattern to strike the coated belt surface. The ions will neutralize the charge in an image pattern and thus allow the image pattern toner to be loosely held in a background of tightly attracted toner. Thereafter, a plain paper sheet is rolled in contact with the surface to pick up the loosely bonded toner and extract an image from the belt onto the plain paper sheet.

The belt is not cleaned, but is recharged to bring up the charge up to full strength in the formerly discharged areas as well as in the areas not discharged and the entire belt is retoned to a uniform density once again for a repeat with the same or a new modulating screen or stencil.

2 Claims, 2 Drawing Figures DEVELOPING METHOD FOR PLAIN PAPER COPYING BACKGROUND OF THE INVENTION The electrostatic copy art has developed upon the principle of a retained electrostatic charge in image configuration upon a photoconductor. which is made visible by triboelectric toner particles attracted to the static charge.

Thus, the art has stabilized on a charge, discharge, tone transfer and clean.

SUMMARY OF THE INVENTION It is an object of this invention to lay down a uniform electric charge. tone that charge. and then neutralize an image area of the toner in order to pick up the released toner in the image configuration, as opposed to standard practice of charge. discharge, and tone.

It is the purpose of this invention to provide a method of producing a plain paper copier or duplicator by releasing an image from a uniform layer of toner and picking that image off onto a carrier sheet.

It is a further object of this invention to eliminate the need to clean a toned surface after an imprint transfer.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic illustration of apparatus suitable to carry out the method of this invention, and

FIG. 2 is a section taken along line 22 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT A belt I is made with a conducting backing 12. The backing is preferably metal. The backing 12 is coated with a dielectric surface 14. The preferred dielectric will be a material such as the commercially available products known as Nylon, Teflon or Mylar. These materials are examples of that kind of dielectric material which will accept a static electric charge on the surface thereof and not lose that charge over an extended petied at time. Nylon is the registered trademark of Dupent Corporation. Teflon is the trademark of Dupont Corporation for a product known chemically as polylliafluoroethylene. Mylar is a Dupont trademark for a pan ester film.

The belt is shown as a horizontal endless belt reeved around two rollers 16.

The method to be carried out of producing plain paper copies of data sheets in a reverse order from standard practice is accomplished by flooding the surface 14 with a uniform charge by means of a cornona device 20. A corona device is well-known in the photocopy art and consists usually of a wire or braid of wire behind a reflector and connected to a source of high voltage.

After the dielectric surface I4 is flooded with a charge, whether negative or positive it does not matter. the charge is then uniformly toned by means of any conventional toning device. illustrated as being a mag netic brush 22. Cascading and other types of toning systems are optional. An example of a brush toner may be seen in US. Pat. No. 3.387.586.

The brush 22 operates to pick up and supply toner from a toner supply source illustrated diagrammatically by a container 24.

The next step in the method is to release toner from the uniformly toned dielectric surface 14 in an image configuration which is to be copied or reproduced. A stencil screen 30 is illustrated as an ion modulating device to filter out a stream of ions produced by a corona device 32. The stencil screen 30 may literally take the form of a metal stencil with the image pattern cut in the metal. The ion discharge produced by the corona device 32 is then permitted to pass through the stencil only in the passages provided by the cut pattern in the stencil.

Also well-known in the art is an imaged photoconducting screen which consists of a photoconductor coated fine metal screen with some areas charged in such a manner as to repel ion flow and other areas uncharged or discharged in an image patter to allow the passage of the ions produced by the corona device 32. These devices are known and are mentioned only as examples.

The stencil screen 30 is moved into position Over the upper run of the belt 10 and the corona device 32 caused to emit a pattern of ion particles through the screen to the belt surface to neutralize those charges produced by the uniform deposition of the corona device 20. This results in a field of toner particles in which the background is uniformly adhering to the belt surface by means of the electrostatic charge, and an image area within the field wherein the toner is lying loose because of the discharge of the image holding field.

Thus. the belt 10 is advanced to a station 34 where a pressure roller 36 presses a piece of plain paper 38 against the surface 14 and causes the loose image area toner to adhere to the paper. If necessary or desirable. a field device may be established behind the paper to help attract the toner from the surface 14 to the plain paper 38.

After transfer of the image to the plain paper 38, paper 38 may be treated by any device for fixing the toner in a known manner. Pressure. heat, and/or solvent fixing are devices wellknown in the art.

After the image has been lifted from the surface of the belt 10, the belt then proceeds around the end of roller 16 and the areas previously neutralized are reflooded with a new charge from the corona device 20 and if the charge on the balance of the background has become weak, the strength of the charge is reinforced. Then the belt is retoned in the manner described, and prepared for a second imprint.

This invention is directed to developing methods and not to imaging and fixing devices, or related equipment. Therefore, an optical station 40 for producing an optical image of an original document 42 onto a screen is illustrated in FIG. 1 only as a suggested means for producing a corona modulating screen for use as described. There are many and various ways or producing screens and stencils, known to those familiar with this art.

What is claimed is:

l. The method of producing plain paper copies of data sheets by first toning a carrier surface and thereafter imaging, comprising the steps of:

1. providing a dielectric surface with a conducting back 2. applying a uniform electrostatic charge to said dielectric surface 3. applying a triboelectric toner in a uniform coating onto said charged dielectric surface Ill aging and thereafter toning.

2. In the method of claim 1. step (5) comprises placing a sheet of :plain paper in contact with said dielectric surface and applying a bias charge on the side of said sheet opposite said dielectric surface to attract the loosened toner. 

1. The method of producing plain paper copies of data sheets by first toning a carrier surface and thereafter imaging, comprising the steps of:
 1. providing a dielectric surface with a conducting back
 2. applying a uniform electrostatic charge to said dielectric surface
 3. applying a triboelectric toner in a uniform coating onto said charged dielectric surface
 4. neutralizing the electrostatic charge in a pattern corresponding to said data sheet; and thereby substantially loosening said toner from said dielectric surface; and
 5. physically attracting said loosened toner onto a final copy carrying sheet; Whereby, the dielectric sheet is toned and thereafter imaged as contrasted with the common methods of imaging and thereafter toning.
 2. applying a uniform electrostatic charge to said dielectric surface
 2. In the method of claim 1, step (5) comprises placing a sheet of plain paper in contact with said dielectric surface and applying a bias charge on the side of said sheet opposite said dielectric surface to attract the loosened toner.
 3. applying a triboelectric toner in a uniform coating onto said charged dielectric surface
 4. neutralizing the electrostatic charge in a pattern corresponding to said data sheet; and thereby substantially loosening said toner from said dielectric surface; and
 5. physically attracting said loosened toner onto a final copy carrying sheet; Whereby, the dielectric sheet is toned and thereafter imaged as contrasted with the common methods of imaging and thereafter toning. 